N-aminoalkylmorpholine viscosity stabilized polyamide and process for making same



Patented Feb. 12, 1952 UNITED STATES rarEN'fr oFFicE v N-jAMiNoALKYLMoRPHoLINE "vIsoosrrY sTAILIzED Permit/111m` AND .PROCESS FOR MAKING SAME YFrederick vKingsbury Watson, Wilmington, Del., v assignor'to E. I. du Pont de Nemours and Com- Wal'e No Drawing.

This invention relates to polymeric materials,

and more particularly to improvements in the preparation of polyamides and to the products thus produced. 4 4 l In Patents 2,071,250, 2,071,253 vand'2,130,948 are disclosed high molecular weight 'polyamides which 'are 'capable of being formed into useful `bers.v

These fiber-forming polyamides are "referred to 'as superpolyamides. Theyare made by heating aminoacids, or by heating diaminesw'ith dibasic carboxylic acids under conditions causing amide formation. ALinear condensation occurs with the formation of 'polyamides In the case vof diamines and "diba's'ic carboxylic 'acids y(which vin this specification and lin the Aforming property does not generally appear until the polymers have an intrinsic viscosity 'of at least 0.4. These superpoly-ami'des vappearto be crystalline and can be convertedinto Vvery useful fibers," among other methods, by melt "spinning, i. e., by extruding the molten polymer through small orifices, e. g., a spinneret, and then colddrawing, that is drawing at a temp'raturebelow the melting point of the polymer `or stretching the resultant laments until they sh'ow ,fiber orientation. In many instances this method of spinning is simpler and more rv:economical than conventional methods of spinning from solution.

However, most superpolyamides, and particularly those most useful for the preparation of textile j fibers, have high melting points, often in the neighborhood f 20G-300 Cl `t the 'tempratures required to spin such polymers "from a melt (generally 10 to 50 C. above their'meflting points) 'the polymer mass becomes more viscous.

'relative viscosity 'greater than 40. y v I I `A`cosity is determined in a conventional'Ostwald "'pa'iiy, Wilmington, Del., a corporation of lDela.- l

Application Febriia'r'y 3,1950, Serial No.,142,363 1'z claims. (orzovsof ning operation. Moreover, in order to obtain vlilaments 'of uniform denier throughout the spinning operation, it is necessary'to increase the temperature 'and/or the pressure of the molten polymer as Further, it y'is doult to ,2. Polyamide lieti/'i119 a (Relative vVS- tviscometerat C. HA solution -'f the polyamide is prepared in'90% fornic acid having a concentration of llgrans per 100 `efe. solvent. The ltime required lidr a given volume Fof this solution to-p'ass thru the viscome'tr diyided by the time required to p'as's v'ail 'ed'al volume of solvent thrutheviscometer is taken as the r-rel'a- `tive viscosity of the polymer.) In order 'to overcome ythis difficulty ith'asbeen 'proposed in the mentioned 'Patent 12,130,948 to use a small `raicess l(up Ito 5 molar per cent) 'of either the 'diamine 0l' the diba'SiC carboxylic acid iii `the plpaatibn V'of the polyamide. 'This gives a 'polymer`whose terminal 'groups are essentially al1 amino or all carboxyl groups depending upon whether the diamine or thedibasic carboxylic 'acid 'was used in excess. For example, the formula 'of a polymer :prepared with excess dibasic carboxylic acid may `be represented as follows:

. OocG'oomHGNiiCoGconheated atr their 'melting point.

NHGNHCOG'COOH (B) Thes'epolymers, "which are essentially viscosity stable, are claimed i'nPat'ent 2,130,948.

An object of this invention is to prepare poly- 'amides which vdo not undergo further reaction when heated under polymerizing conditions. A further vobject is to prepare rp'olyamides which do not undergo 'appreciable viscosity change when A still further "object is to prepare -polyamides which can be 4.5gpo'lyamide-forming reactants, particularly diathese products undergo further polymerization. i

This fact is also true ofpoiyamides-defived from amino acids. This furtherpolymeriztion makes it diicult to prepare uniformlamets' fromthe pclymer, Vfor when a sample of the'lattr is heated in a melt spinning device, the laments Hrst extruded consist of a lower molecular.'weightpoly mer than those extruded near the eridof "thGi-"spin` y .dyeing properties.

'spun into iibers froinfmelt without undergoing substantial change in viscosity. Still another object is to prepare polyamides possessing superior Other objects will appear hereinafter.

-These objects are accomplished by heating minet-dibasic carboxylic acid mixtures in the presence of an N-amino-alkylmorpholine of the Aformula GHz-C 2 wherein 11, is a whole number from 2 t0 12 inclu- 1'sive, and the nitrogen atoms are separated by at 'leat two carbon atoms.

3 I have found that viscosity stable polyamides of improved dyeing properties can be obtained by preparing polyamides in the presence of a small amount, generally 0.1 to molar per cent 4 carboxylic acid salt is meant the quantity of salt obtained from one mol of diamine and one mol of dibasic car'bo'xylic acid. More than 5 mol per cent of stabilizer may be used, however, when it of an N-aminoalkylmorpholine such as described 5 is desired to prepare products of low viscosity. above based on the diamine content of the poly- For the preparation of liber-forming polyamides amide. These substances which are added to imit is generally desirable to have theultlmate inpar-t viscosity stability to the polyamide will be trinsic viscosity of the polyamide in the range referred to as the stabilizer. The stabilizer from 0.5 to 2.0. The quantity of stabilizer reserves the purpose of allowing the production of quired toobtain a product of a given intrinsic any desired molecular Weight polyamide by conviscosity can bedetermined by experiment. When trolling the number of carboxyl and amine the quantity and conditions for the preparation groups. Thus, if a polyamide is desired having of a given product have been determined, the a certain relative viscosity, it is achieved by the A results can be duplicated fairly readily. The simple procedure of incorporating a predeterquantity of stabilizer necessary to prepareaprodmined amount of stabilizer with the initial reuct of a given intrinsic viscosity [nl can alsolbe actants. When the desired viscosity range is determined, roughly at least, by the following reached, equilibrium is established and the polli;- equaton merization stops. The ultimate viscosi y of t e 01s Stabilizer polyamide obtained is dependent upon the M required=ll)llll -OfSau; nl-olb'0E-a1t amount of stabilizer added: the more stabilizer y 161000 [n] that iS added the 10Wer the ultimate VSCOSY- in whichsalt refers to the diamine-dibasic car- The Stabilizer may be added to the polyamidebcxyiic acid salts or to the mixture cf polyamideforming reactants before, during, or after polyforming reactants used. merization. A stabilizer may also be added to While the invention has been described with (heated with) a preformed polymer Vto 10We1 special reference to the preparation of viscosity its viscosity. i stable polyamides of the diamine-dibasic car- Representative examples of specic N-alkyl bcxylic acid type, it is also applicable tc the morpholines Suitable for purposes 0f this invenpreparation cf polyamides from amino acids tion are! N-amnoethylmol'pholne. N-amIlOPrO' 30 whose amino nitrogen cari-ies at least one hy- Pylmorpholine, N aminObutylmOrphOln. N drogen atom. It is possible, for example, to preaminoisobutylmorpholirie, N-amino-sec-butyl- .para viscosity stable polyamides by heating a m01`ph01ne, N-aIIllO-t-blltylmlphlne, N-am'f. polymerizable amino acid or an amide-forming noemylmorpheline. N-emnoisoemylmorpholine, derivative thereof in the presence cf the stabil- N-aminoisohexylmorpholine, N-aminoisoheptylizei'. merpholna N-eminosooetylmorpholine, N-ami- The follcwingexamples are further illustrative nO-Z-ethylhexylmolphOline, Namn0S0dCy1 of the principles andV practice of this invention. morpholine, and N-amnosolaurylmorpholine. Parts are by weight unless otherwise indicated..

The term polyamide-forming reaetent is used To parts of the dry salt (diamine-dicarboxto designate a bifunctional compound which 4o y1ic acid) is added an amount of stabilizer as yieldsa polyamide when heated alone or in adshownA below, together with 50 parts of water. i mixture with a complementary polyamide-form- This is heated in a closed autoclave until a presing leatant- It `includes POlymerizable amino sure of 250 pounds per square inch is reached. acids or amide-forming derivatives thereof (i. e., This pressure is maintained by bleeding off steam all ester. acid halide, amide, 01 anhydride), di5 w-hile .the temperature is gradually raised over a amines, dicarboxylic acids, and amide-forming period of.34 hours until 2'75a C. is reached. This derivatives of dibasic carboxylic acids. In contemperature is maintained and the pressure is trast to the polyamide-forming reactants, the reduced to atmospheric over a period of two monofunctionalamide-forming reactants are not hours. Heating isl continued at 275 C. and alone capable of yielding polymers. 59 atmosphericA pressure for one-half hour. The It has been stated that the quantity of stapolymer is then extruded onto a water-cooled bilizer employed in the preparation of the prodwheel and broken into chip. The chip is suitable ucts of this invention determines the ultimate for charging into a conventional melt-spinning viscosity of the product. Quantities of stabilizer unit for the production of yarns, films or molded from 0.1 to 5.0, and preferably from 0.3 to 1.5, articles. The table below shows the amounts and molar per cent of the diamine are usually used kinds of stabilizers used, together with the rein the preparation of viscosity stable polyamides sults obtained. Several control examples (no described herein. By a mol of diamine-dibasic stabilizer) were run for comparative data.

- d Y A nit. of Stsitnmpic Polymer stabiiircr ,2517125221213 Rlglyff Parts Salt Control... A None 40-60 `1 A 'N-ai'ninoethylmorpholine. 0.2510 31 A N'amiiiopropylmorpholine.. 0.1055 37 A N-aininobutylmorpholine.-. 0.3050 30 A N-aminoamylmorpholne 0.3320 3l A N-aminohexylmorpholine 0.3590 3l B, None .-7 50-65 B Namino`ethylmorpholine 0.1495 38 B N-aminopropylmorpholine.. 0.2780 20 0 None 110-130 C N-aminopi'opylmorpllo1ine 0.2280 20-25 A.-Polyliexamethylene adipamide. B.Polyhexamethylene sebacamide.

V Po'lyamides `of this invention can be prepared by the general methods 'described in the'previ- .ously mentioned applications. Thus, it is possible to prepare lthe products of this invention by reacting polyamide-forming reagents -With a viscosity stabilizer in the absence' of a -solvent (fusion method), in the presence of an inert solvent such as a monohydric phenol, or in the presence of Han inert non-solvent such as a hydrocarbon or `inert chlorinated hydrocarbon. Mixtures of solvents and non-'solvents may also be used. The reaction is generally carried out in the neighborhood of G-300 C. and preferably 220-290 C. The reaction may be eiected at ordinary, increased, or decreased pressure. Often it is desirable, especially in the last stagecf the reaction, to employ conditions, e. g., reduced pressure, which will aid inthe escape .of the Ywateror other 'by-products formed in vthe reaction.

To prepare polyamides of the diamine-dibasic carboxylic acid type, it is advantageous to use the diamine-dibasic carboxylic acid salt, since this product is lcrystalline and easily obtained in a pure form. However the diamine may be reacted :directly with a dicarboxylic acid or arl-amideforming derivative of a dibasic vcarboxylicacid such as the ester, acid chloride, amide, or anhydride. The invention, as already indicated, is applicable to the preparation of viscosity stable amino acid polymer. The preparation of viscosity stable interpolymers, vfor example, those obtained by reacting anamino acid With a diaminedibasic carboxylic .acid mixture or a mixture of diamine-dibasic dicarboxylic acid salts,V is also within the scope of this invention.

The diamines used in the practice of this invention are those whose amino nitrogens carry at least one hydrogen. VThe invention herein described is very useful in the preparation oi?l Y viscosity vstable superpolyamides from diamines of the formula II2NCHzRCH2NH2 anddicarboxylic acids of the formula HOOCCHRCI-IzCOOH in which R and R represent divalent hydrocarbon radicals free from non-benzenoid unsaturation, that is, they are free from aliphatic (oleiinic or acetylenic) unsaturation and in which R has a vchain length of at least two carbon atoms. It is Vespecially useful when'applied to the preparation in the preparation of polyamides suitable for melt spinning, this by no means limits' the extent or utility of the present invention. Viscosity stable ber-forming polyamides are also useful in spinning from solution and in otherapplications, for example, in the preparation of lms, ribbons, bands, sheets, bristles, molded articles, and the like. Non-ber-forming polyamides, e. g., resinous polyamides, can also be obtained in the viscosity stable form by the methods of the present invention. Such products are particularly useful in the preparation of coating, molding, sizing, impregnating, adhesive, and related compositions. Itis within the scope of this invention to mix Viscosity stable polyamdes with each other as well as with other ingredients, such as cellulose derivatives, e. g., ethyl cellulose, benzyl Cellulose, cellulose acetate, nitrocellulose;

natural resins; syntheticresins, le. g.; polyhydric alcohol-polybasic acid. resins. vinyl Y resins, .phe-

Asmany apparently widely different embodi-` ments of vthis.,invention may be made. without departing from vthe spirit .and scope thereof,v it is to be understood that TIl do `not `limit inyselfto the vspeciiic embodiments 4thereoffexcepty as deiined in the appended claims. `.Iclaimz l l. Linear polycarbona'mides prepared 'from reactantsof ,the class consistingof (l) diamines and -dibasic carboxylic acids and their amideforming derivatives, and (2) monoami'no'jcarboxylic acids and their amide-forming derivatives, viscosity-stabilized with an N-aminoalkylmorpholine of the formula:

wherein n, is a while number from 2 tov .12 inclusive, and the nitrogenv atoms are separated by at least two carbon atoms.

2. Film-forming linear '.superpolyamides of diamines of the formula-NHzCHzRCHzNHz and dibasic carboxylic acids of the formula vHooo---oH212clara-COOH i a and R' `in said formulae being divaienrhydrocarbon radicals freelfrom aliphatic unsaturation and R having a chain Vlength of at least two carbon atoms, Viscosity-stabilized with an N -aminoalkylmorph'oline of the formula;

CH2-CH2 y N-VC-..H2-NH2 wherein n is a whole number from 2 to 412 inclusive` and the .nitrogen vvatoms vare .separated .by

.at least two .carbon atoms, vsaid polyamidesyilding rthelliydrochloride of theN-aminoalkylmor- 7. The product of claim 2 wherein the stabilizer is N-aminoamylmorpholine of the formula:

CHT-CH, o/ NqcHm-NH;

CH2-CHI 8. The product of claim 2 wherein the stabilizer is N-aminohexylmorpholine of the formula:

CHz--CH 9. A process for making fiber-forming substantially viscosity-stable linear superpolyamides which comprises reacting polyamide-forming reactants of the class consisting of (1) diamines and dibasic carboxylic acids and their amideforming derivatives, and (2) monoamine carboxylic acids and their amide-forming derivatives, under polymerizing conditions in the presence of from 0.1 to 5.0 molar per cent, based on the diamine reactant. of an N-aminoalkylmorpholine of the formula.:

GHz-CH2 N-C,.H1NH2 CHz--CHz wherein n is a whole number from 2 to 12 inclusive and the nitrogen atoms are separated by at least two carbon atoms, as stabilizer.

10. The process of claim 9 wherein the stabilizer is N- aminopropylmorpholine of the formula amides, with from 0.1 to 5.0 molar per cent, based on the monomeric diamine reactant represented in said polyamides, vof an N-aminoallylmorpholine of the formula:

wherein n is a whole number from 2 to 12 inclusive and the nitrogen atoms are separated by at least two carbon atoms.

12. A process for making fiber-forming substantially viscosity-stable polyamides which comprises heating under polymerizing conditions a y mixture of polyamide-forming reactants com- 8 prising substantially equimolecular proportions of a diamine of the formula II2l\ICHzRCHzNHi` and a compound of the class consisting of dicarboxylic acids of the formula HOOCCHzR'CHzCOOH and amide-forming derivatives of such acids, R and R. in said formulae being divalent hydrocarbon radicals free from aliphatic unsaturation and R. having a chain length of at least two carbon atoms, in the presence of from 0.1 to 5.0 molar per cent, based on the diamine, of a viscosity stabilizer of the formula:

CHI-CH:

wherein n is a whole number from 2 to 12 inclusive and the nitrogen atoms are separated by at least two carbon atoms.

13. The process of claim 12 wherein the viscosity stabilizer is N-aminopropylmorpholine of the formula: Y

14. The process of claim 12 wherein the viscosity stabilizer is N-aminoethylmorpholine of the formula:

CH2-CH2 o N-(CHm-NH,

CH2-G z 15. The process of claim 12 wherein the viscosity stabilizer is N-aminobutylmorpholine of the formula:

16. The process of claim 12 wherein the viscosity stabilizer is N-aminoamylmorpholine of the formula:

i 17. The process of claim 12 wherein the viscosity stabilizer is N-aminohexylmorpholine of the formula:

CH2-CH;

O\ N-(CHz) c-NHI CHr-CH:

FREDERICK KINGSBURY WATSON.

REFERENCES CITED The following references are oi' record in the l file of this patent:

UNITED STATES PATENTS Number Name Date 2,142,007 Schlack Dec. 27, 1938 2,174,527 Peterson Oct. 3, 1939 

1. LINEAR POLYCARBONAMIDES PREPARED FROM REACTANTS OF THE CLASS CONSISTING OF (1) DIAMINES AND DIBASIC CARBOXYLIC ACIDS AND THEIR AMIDEFORMING DERIVATIVES, AND (2) MONOAMINO CARBOXYLIC ACIDS AND THEIR AMIDE-FORMING DERIVATIVES, VISCOSITY-STABILIZED WITH AN N-AMINOALKYLMORPHOLINE OF THE FORMULA: 